Impact of body mass index on outcomes of inpatients with vertebral compression fractures in Japan: A retrospective cohort study.

Abstract

The present study examined the relationship between body mass index and the ability to perform the activities of daily living in patients with vertebral compression fractures. A retrospective cohort analysis of patients aged >65 years hospitalized with a vertebral compression fracture was carried out using a nationwide database in Japan. Body mass index was categorized as underweight (<18.5 kg/m2 ), normal weight (18.5-22.9 kg/m2 ), overweight (23.0-27.4 kg/m2 ) and obese (≥27.5 kg/m2 ) according to the World Health Organization criteria for the Asia-Pacific region. The primary outcome was Barthel Index gain, namely, the change in the Barthel Index score at discharge from that at admission. Secondary outcomes were the length of hospital stay and readmission within 30 days of discharge. Among 41 423 participants, 24.5% were classified as underweight, excluding those with missing body mass index data. The underweight group had a significantly lower Barthel Index gain than the normal, overweight and obese groups (median 20 vs 25 vs 30 vs 30, respectively, P < 0.001). The underweight group also had longer hospital stays and higher 30-day readmission rates than the other groups. A multivariable analysis showed that being underweight was independently associated with a Barthel Index gain -3.63 points (95% confidence interval -4.58 to -2.68) lower than normal weight. Furthermore, being underweight was an independent variable affecting the length of hospital stay and readmission within 30 days (P < 0.001). In patients with vertebral compression fractures, being underweight leads to lower Barthel Index scores, longer hospital stays and increased readmissions within 30 days of discharge. Geriatr Gerontol Int 2023; 23: 788-794.